In the related art, there is a known parallel link robot provided with: a base portion on which three motors are disposed; a movable portion disposed below the base portion; and three arms that link the base portion and the movable portion so as to be parallel to each other and that are driven by the motors (for example, see Japanese Unexamined Patent Application, Publication No. 2015-85486 and Japanese Unexamined Patent Application, Publication No. 2009-255193). The movable portion is provided with a wrist shaft that is rotatable about a vertical axis with respect to the movable portion. An end effector, such as a hand, can be attached to a wrist flange at the lower end of the wrist shaft, and it is possible to change the orientation of the end effector about the vertical axis by means of rotation of the wrist shaft with respect to the movable portion.
Meanwhile, in order to perform phase-matching between a rotating member and a rotating shaft of the rotating member in a simple manner, marks such as marking-off lines, which are individually provided in advance on the rotating member and the rotating shaft, are used (for example, see Japanese Unexamined Patent Application, Publication No. 2016-048093).